Polyol composition of the two-part system for foam grindstone, two-part curable composition for foam grindstone, foam grindstone, and process for production thereof

ABSTRACT

A polyol composition contains a polyaminochlorophenylmethane mixture (A) and a polyol (B), in which the component (A) is uniformly dissolved in the component (A) in a weight ratio of 30/70 to 60/40. The component (A) includes 50 to 70% by weight of a specific binuclear polyaminochlorophenylmethane compound, 20 to 40% by weight of a specific trinuclear polyaminochlorophenylmethane compound and 5 to 10% by weight of a specific tetranuclear or higher polyaminochlorophenylmethane compound. The polyol composition exhibits excellent miscibility and dissolution stability, is liquid and enables molding of a foamed article for abrasive in a simple two-component mixing casting machine. According to the present invention, water serving as a foaming agent can be added to the polyol composition containing MBOCA, and the composition for a two-component curable abrasive foam can be held to a temperature equal to or lower than the boiling point of water, thus avoiding water from evaporating upon molding. The resulting abrasive foam has a uniform density distribution and exhibits excellent mechanical properties. A method for satisfactorily producing such an abrasive foam is also provided.

TECHNICAL FIELD

The present invention relates to a polyol composition for atwo-component curable abrasive foam which exhibits satisfactorydissolution stability, a composition for a two-component curableabrasive foam, an abrasive foam, and a method for producing an abrasivefoam.

BACKGROUND ART

An amine compound, 4,4′-diamino-3,3′-dichlorodiphenylmethane as a rawmaterial for urethane resins, is generally referred to as MOCA or MBOCAand is used in the production of urethane foam for abrasive andpolishing pads (for example, Japanese Patent Application, FirstPublication No. H2-232173 (Example 1) and Japanese Patent Application,First Publication No. 2002-194104 (claim 1, and Example 1 in paragraph[0034])).

The polishing pad disclosed in Japanese Patent Application, FirstPublication No. H2-232173, for example, is prepared in the followingmanner. Water (foaming agent) and an epoxy resin powder are added to atoluene diisocyanate (TDI)-based urethane prepolymer, followed byaddition of a catalyst, a silicone oil and4,4′-diamino-3,3′-dichlorodiphenylmethane (hereinafter also referred toas MBOCA). The mixture is cast in a mold using a casting machine, isfoamed and thereby yields a block molded article. The block moldedarticle is sliced to yield the polishing pad.

In this procedure, a two-component mixing casting machine is generallyused. This is because MBOCA used herein has a melting point of about110° C., water has a boiling point of 100° C., and the reaction betweenthe urethane prepolymer and MBOCA (crosslinking reaction) and thereaction with water (foaming reaction) must occur simultaneously. Inthis molding process, MBOCA must be heated to 110° C. or higher so as toliquefy MBOCA to be suitable for mixing. In contrast, water serving asthe foaming agent must not be incorporated into the isocyanate urethaneprepolymer in advance, since water reacts with the isocyanate. Thus,water is added to MBOCA in advance. However, water evaporates uponheating of MBOCA at 110° C., i.e., the melting point of MBOCA, or higherso as to liquefy MBOCA. Thus, a desirable foam is not prepared. Morespecifically, the resulting foamed molded article exhibits increaseddensity variation and lacks uniformity in density distribution which isessential to an abrasive.

Japanese Patent Application, First Publication No. 2002-194104 disclosesa molded article prepared by, instead of foaming with water, mixing aprepolymer having a terminal isocyanate group with fine particlestreated with a silicone surfactant, adding MBOCA to the mixture andcasting the resulting mixture into a mold. Even treated with asurfactant, however, such fine particles are difficult to be uniformlymixed with the prepolymer having a terminal isocyanate group, failing toyield a molded article having a uniform density distribution.

DISCLOSURE OF INVENTION

Accordingly, an object of the present invention is to provide a polyolcomposition for a two-component curable abrasive foam, which exhibitssatisfactory dissolution stability, can stably yield a molded articlefor use as an abrasive foam in a two-component mixing casting machineand can yield a urethane foam abrasive having excellent mechanicalproperties as an abrasive foam and exhibiting a uniform densitydistribution. Another object of the present invention is to provide acomposition for a two-component curable abrasive foam, an abrasive foamand a method for producing an abrasive foam using the polyolcomposition.

Specifically, the present invention provides a polyol composition for atwo-component curable abrasive foam, containing (A) apolyaminochlorophenylmethane mixture and (B) a polyol, thepolyaminochlorophenylmethane mixture (A) containing:

50 to 70% by weight of a binuclear polyaminochlorophenylmethane compoundrepresented by the following formula:

(wherein X independently represents a chlorine atom or a hydrogen atom),

20 to 40% by weight of a trinuclear polyaminochlorophenylmethanecompound represented by the following formula (hereinafter referred toas “trinuclear compound”):

(wherein X independently represents a chlorine atom or a hydrogen atom),and

5 to 10% by weight of a tetranuclear or higherpolyaminochlorophenylmethane compound represented by the followingformula (hereinafter referred to as “tetranuclear compound”):

(wherein X independently represents a chlorine atom or a hydrogen atom;and n represents an integer of 3 or greater), wherein thepolyaminochlorophenylmethane mixture (A) is uniformly dissolved in thepolyol (B), and the weight ratio of (A) to (B) ((A)/(B)) stands at 30/70to 60/40. The present invention further provides a composition for atwo-component curable abrasive foam, an abrasive foam and a method forproducing an abrasive foam using the same.

The binuclear, trinuclear, and tetranuclear or higherpolyaminochlorophenylmethane compounds represented by Chemical Formulae1 to 3 include compounds wherein Xs are all hydrogen atoms. In thepresent description, these compounds including such compounds wherein Xsare all hydrogen atoms are referred to as “polyaminochlorophenylmethanecompound(s)” for the sake of convenience.

BEST MODE FOR CARRYING OUT THE INVENTION

The component (A) for use in the present invention is apolyaminochlorophenylmethane mixture (hereinafter referred to as“mixture (A)”). The mixture (A) comprises 50 to 70% by weight of thebinuclear polyaminochlorophenylmethane compound represented by ChemicalFormula 1, preferably 4,4′-diamino-3,3′-dichlorodiphenylmethane(hereinafter referred to as MBOCA); 20 to 40% by weight of thetrinuclear polyaminochlorophenylmethane compound represented by ChemicalFormula 2; and 5 to 10% by weight of the tetranuclear or higherpolyaminochlorophenylmethane compound represented by Chemical Formula 3.The mixture (A) is obtained as a product mixture including trinuclear,tetranuclear or higher polyaminochlorophenylmethane compounds in theproduction of binuclear MBOCA using chloroaniline and formalin as rawmaterials. The mixture (A) is solid at normal temperature (roomtemperature), and is melted and becomes liquid at a temperature ofpreferably 80° C. or lower, and more preferably 50° C. to 80° C.

If the mixture (A) has a composition out of the above-specified range,the polyaminochlorophenylmethane mixture (A) precipitates from thepolyol (B) during long-term storage, and the resulting compositionexhibits deteriorated dissolution stability. Such a mixture does notyield a product having satisfactory physical properties and a uniformdensity distribution as a foamed polyurethane abrasive.

The polyol (B) for use in the present invention is a polyol containingan ether bond in a principal chain thereof and having a molecular weightof preferably 100 to 1500, more preferably 500 to 1200, and/or a polyolcontaining methyl group in a side chain thereof and having a molecularweight of 50 to 500. These polyols each have at least two, preferablytwo or three, terminal hydroxyl groups, are miscible with the mixture(A) and are liquid at normal temperature (at 25° C.) or, even if solidat normal temperature (at 25° C.), have a melting point of 60° C. orlower. Among them, polyols that become miscible with the mixture (A)upon heating are preferred. Examples of the polyol containing an etherbond in a principal chain thereof are polyethylene glycols,polypropylene glycols, polyethylene propylene glycols,polytetramethylene glycols, diethylene glycol, triethylene glycol,dipropylene glycol and tripropylene glycol. Among them, at least oneselected from polytetramethylene glycol and polypropylene glycols ispreferred. Each of these may be used in combination.

Examples of the polyol containing methyl group in a side chain thereofare 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and polyesterpolyols derived from these glycols and adipic acid. Each of these can beused in combination.

The polyol (B), in which the mixture (A) is dissolved, is selected fromamong the above-mentioned polyols and, in the production of an abrasivecontaining a grain (abrasive grain), is selected according to the amountof the grain. This is to avoid an excessively high viscosity of thecomposition for a two-component curable abrasive foam caused by additionof such grains, which makes the composition unsuitable for molding in aregular two-component mixing casting machine. The viscosity of thepolyol (B) is preferably 50 to 1000 poises (at 25° C.).

The weight ratio ((A)/(B)) of the mixture (A) to the polyol (B) in thepolyol composition of the present invention stands at 30/70 to 60/40. Ifthe weight percentage of the mixture (A) exceeds 60, the polyolcomposition for a two-component curable abrasive foam (1) exhibitsdeteriorated dissolution stability, thus inviting precipitates from themixture (A), which may lead to clogging of the two-component mixingcasting machine. If it is less than 30, the abrasive foam exhibitsremarkably deteriorated mechanical properties and is less worthy as anabrasive. The polyol composition of the present invention is preferablyliquid at 25° C. and preferably has a viscosity of 300 to 3000 poises(at 25° C.). The polyol composition of the present invention has anNH₂.OH equivalent of preferably 50 to 300 and more preferably 100 to250. The polyol composition is prepared by melting the mixture (A) byheating preferably at 100° C. to 120° C. and mixing the melted mixture(A) with the polyol (B) preferably heated at 80° C. to 110° C. in theabove-specified weight ratio. In this procedure, the polyol compositionis preferably subjected to dehydration at 100° C. to 110° C. at areduced pressure of 5 to 10 mmHg for 30 minutes to 2 hours before thecompletion of its preparation.

The water (3) for use in the present invention is used as a foamingagent and can be any of water without contamination or turbidity and tapwater. Among them, ion-exchanged water and pure water are preferred. Theamount of the water (3) is preferably 0.01 to 5% by weight and morepreferably 0.05 to 2% by weight based on the weight of the polyolcomposition comprising the components (A) and (B).

The polyisocyanate (2) for use in the composition for a two-componentcurable abrasive foam of the present invention is preferably a urethaneprepolymer having a terminal isocyanate group, which has been preparedby the reaction of a polyisocyanate compound (2-1) with a polyol (2-2).

Examples of the polyisocyanate compound (2-1) are 2,4- or 2,6-toluenediisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylenediisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- or1,4-diisocyanate,1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (also knownas isophorone diisocyanate; hereinafter referred to as IPDI),bis-(4-isocyanatocyclohexyl)methane (hereinafter referred to as“hydrogenated MDI”), 2- or4-isocyanatocyclohexyl-2′-isocyanatocyclohexylmethane, 1,3- or1,4-bis-(isocyanatomethyl)-cyclohexane,bis-(4-isocyanato-3-methylcyclohexyl)methane, 1,3- or1,4-α,α,α′,α′-tetramethylxylylene diisocyanate, 2,2′-, 2,4′- or4,4′-diisocyanatodiphenylmethane (hereinafter referred to as MDI),1,5-naphthalene diisocyanate, p- or m-phenylene diisocyanate, xylylenediisocyanate and diphenylmethane-4,4′-diisocyanate. Among them, 2,4- or2,6-toluene diisocyanate is preferred.

The polyol (2-2) preferably has a molecular weight of 500 to 3000.Examples thereof are polyethylene glycols, polypropylene glycols,polyethylene/propylene glycols, polytetramethylene glycols,2-methyl-1,3-propane adipate, 3-methyl-1,5pentane adipate andpolycarbonate polyols. In addition, a glycol having a molecular weightof 50 to 300 may be used in combination. The polyol is more preferably apolytetramethylene glycol or polypropylene glycols having a molecularweight of 500 to 1200.

Toluene diisocyanate-type urethane prepolymers each containing aterminal isocyanate group are more preferred as the polyisocyanate (2)for use in the composition for a two-component curable abrasive foam ofthe present invention. Among them, one having a melting point of 60° C.or lower is further preferred, and one which is liquid at normaltemperature is typically preferred. Typically from the viewpoint ofmechanical strength, the polyisocyanate (2) is preferably apolyisocyanate having an isocyanate equivalent of 300 to 580 and isprepared by the reaction of 2,4- or 2,6-toluene diisocyanate as thepolyisocyanate with the polyol. The above-mentioned other polyisocyanatecompounds can be additionally used in combination.

Examples of the glycol having a molecular weight of 50 to 300 arealiphatic diols such as ethylene glycol, propylene glycol,1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol,tetraethylene glycol, dipropylene glycol, tripropylene glycol,3-methyl-1,5-pentanediol, 2-butyl-2-ethyl 1,3-propanediol and2-methyl-1,3-propanediol; alicyclic diols such as 1,4-cyclohexanediol,1,4-cyclohexanedimethanol and hydrogenated bisphenol A; andtrifunctional or higher components such as glycerol, trimethylolpropaneand pentaerythritol.

In the composition for a two-component curable abrasive foam of thepresent invention, the weight proportions of the polyisocyanate (2) andthe polyol composition (1) comprising the mixture (A), the polyol (B)and water (3) are set so that the amount of OH group and NH₂ groupstands at preferably 0.6 to 1 equivalent, and more preferably 0.7 to0.95 equivalent per 1 equivalent of isocyanate group, wherein the amountof 1 mole of the water is defined as 2 equivalents in terms of OH group.

The polyol composition for a two-component curable abrasive foam of thepresent invention may appropriately further comprise, for example,urethanization catalysts, abrasive grain, foam stabilizers, fillers,pigments, thickening agents, antioxidants, ultraviolet absorbers,surfactants, flame retardants and/or plasticizers. Among them,urethanization catalysts and foam stabilizers are preferably added.

Examples of the urethanization catalyst are nitrogen-containingcompounds such as triethylamine, triethylenediamine andN-methylmorpholine; metal salts such as potassium acetate, zinc stearateand tin octylate; and organometallic compounds such as dibutyltindilaurate. Examples of the foam stabilizer are silicone surfactants suchas Toray Silicone SH-193, SH-192 and SH-190 (products of Dow CorningToray Silicone Co., Ltd.). The amount thereof is preferably 0.01 to 5%by weight based on the weight of the polyol composition.

Preferred examples of the abrasive grain include cerium oxide, zirconiumoxide, silicon carbide and alumina. A foamed molded article prepared bycompounding these materials is useful as a material for producing afoamed urethane abrasive by cutting. Among them, cerium oxide andzirconium oxide are typically preferred.

The average particle size of the abrasive grain is not specificallylimited and is preferably 0.1 μm to 200 μm, depending on the purpose ofpolishing. If the average particle size of the abrasive grain exceeds200 μm, the composition may tend to precipitate in a tank of thetwo-component mixing casting machine and may cause clogging of headnozzles. The abrasive grain precipitates more readily with an increasingaverage particle size thereof. Thus, the structure and number ofrotations of an impeller in the tank of the two-component mixing castingmachine should be set appropriately.

The amount of the grain preferably falls within a range of 10 to 200parts by weight per 100 parts by weight of the total amount of themixture (A) and the polyol (B).

When used in the method for producing an abrasive foam of the presentinvention using the composition for a two-component curable abrasivefoam of the present invention, it is preferred that the polyolcomposition comprising the mixture (A) and the polyol (B) exhibits goodmiscibility between (A) and (B) and be liquid at 25° C., or that thepolyol composition be a uniform liquid mixture when heated at 40° C. to70° C. According to the method, a molded article for abrasive foam isprepared in the following manner. The polyol composition (1) added withthe water (3), and the polyisocyanate, preferably a urethane prepolymercontaining a terminal isocyanate group, (2) are separately placed intoeach tank of a two-component mixing casting machine. The polyolcomposition (1) is heated preferably at 40° C. to 70° C. and thepolyisocyanate (2) is heated preferably at 40° C. to 90° C. These heatedcomponents are mixed in the two-component mixing casting machine toyield a mixture, and the mixture is cast in a mold at a temperature ofpreferably 80° C. to 120° C. and more preferably 90° C. to 110° C. Theproportions of the components are set so that the reaction smoothlyproceeds and foaming and curing occur simultaneously. The resultingarticle is preferably left in the mold at 80° C. to 120° C. for 30minutes to 2 hours, is then taken out from the mold, and is subjected toafter-curing preferably at 100° C. to 120° C. for 8 to 17 hours. Themolded article may be cut into sheets having a thickness of preferably0.5 to 3 mm using a slicer to yield an abrasive foam sheet.

In the production of an abrasive using the composition for atwo-component curable abrasive foam, the abrasive grain can beincorporated into either of the polyol composition (1) and thepolyisocyanate (2) in advance, but is preferably incorporated into thepolyol composition (1) for satisfactory stability of the resultingmixture. For satisfactorily uniform dispersion, the grain is preferablyadded in several installments into the polyol composition comprising themixture (A) and the polyol (B) in advance while agitating in ahigh-speed agitator. The high-speed agitation makes the surface of theabrasive grain more wettable, which avoids aggregation of the abrasivegrain by the action of the air. The mixture is more preferably defoamedin vacuo to evacuate the air from the grain and make the grain morewettable. Higher wettability of the abrasive grain enables the urethaneresin to bind with the abrasive grain more firmly to thereby prevent theabrasive grain from dropping off during polishing. The abrasivepreferably comprises the abrasive grain, but may not comprise theabrasive grain in some applications.

The specific gravity of the two-component curable abrasive foam of thepresent invention is preferably 0.3 to 1.0 when not containing theabrasive grain, and is preferably 0.3 to 1.2 when containing theabrasive grain. The abrasive foam having an excessively low specificgravity may have insufficient strength and may invite remarkable wear.The abrasive foam having an excessively high specific gravity includesfewer pores and may not effectively polish a work.

The polyol composition of the present invention is preferably liquid atnormal temperature. This achieves easier mixing of water, the foamstabilizer and the catalyst. In addition, the amount of the abrasivegrain can be set within a wide range by selecting a suitable polyol. Thepolyol composition of the present invention allows molding in atwo-component mixing casting machine, is free from evaporation of waterand can easily yield a urethane foam for abrasive foam having a uniformdensity distribution and excellent mechanical properties. If the densitydistribution is ununiform, the polishing performance becomes non-uniformand the product cannot be used as an abrasive foam for polishingprecision products such as silicon for the production of semiconductorsand glass for lenses.

EXAMPLES

The present invention will be further illustrated with reference toseveral examples below, which are not intended to limit the scope of thepresent invention. All parts and percentages are by weight.

Example 1 Mixing and Preparation of Mixture (A) and Polyol (B)

A polytetramethylene glycol (PTMG1000, a product of Mitsubishi ChemicalCorporation) as a polyol was placed in a flask and held at 100° C.Separately, a mixture (A) was prepared by dissolving 65% of4,4′-diamino-3,3′-dichlorodiphenylmethane (binuclear compound), 28% of atrinuclear polyaminochlorophenylmethane compound and 7% of atetranuclear or higher polyaminochlorophenylmethane compound at 70° C.The mixture (A) was fused at 120° C. and was added to the polyol in theflask in amounts of 30%, 40%, 50% and 60% based on 70%, 60%, 50% and 40%of the polyol, respectively. The resulting mixture was blended and wassubjected to dehydration at 100° C. to 105° C. at a reduced pressure of5 to 10 mmHg for 1 hour. The product was taken out from the flask aftercooling, to yield a liquid polyol composition.

Comparative Example 1

A polytetramethylene glycol (PTMG1000, a product of Mitsubishi ChemicalCorporation) as a polyol was placed in a flask and was held at 100° C.Separately, a mixture of 82% of4,4′-diamino-3,3′-dichlorodiphenylmethane (binuclear compound), 15% of atrinuclear compound and 3% of a tetranuclear compound was fused at 120°C. and was added to the polyol in the flask in amounts of 30%, 40%, 50%and 60% based on 70%, 60%, 50% and 40% of the polyol, respectively. Theresulting mixture was blended and was subjected to dehydration at 100°C. to 105° C. at a reduced pressure of 5 to 10 mmHg for 1 hour. Theproduct was taken out from the flask after cooling, to yield a liquidpolyol composition.

Comparative Example 2

A polytetramethylene glycol (PTMG1000, a product of Mitsubishi ChemicalCorporation) was placed in a flask and was held at 100° C. Separately,PANDEX E (a product of Dainippon Ink and Chemicals, Inc.) containing 98%by weight or more of 4,4′-diamino-3,3′-dichlorodiphenylmethane(binuclear compound) was fused at 120° C. and was added to the polyol inthe flask in amounts of 30%, 40%, 50% and 60% based on 70%, 60%, 50% and40% of the polyol, respectively. The resulting mixture was blended andwas subjected to dehydration at 100° C. to 105° C. at a reduced pressureof 5 to 10 mmHg for 1 hour. The product was taken out from the flaskafter cooling, to yield a liquid polyol composition.

Example 2 Mixing and Preparation of Mixture (A) and Polyol (B)

A polyol mixture (B) was prepared by adding 34.1 parts of diethyleneglycol (a product of Mitsubishi Chemical Corporation) to 500 parts of apolytetramethylene glycol (PTMG1000, a product of Mitsubishi ChemicalCorporation) and was held at 100° C. The mixture (A) used in Example 1was fused at 120° C. and was added to the polyol mixture (B) in theflask in amounts of 30%, 40%, 50% and 60% based on 70%, 60%, 50% and 40%of the polyol mixture, respectively. The resulting mixture was blendedand was subjected to dehydration at 100° C. to 105° C. at a reducedpressure of 5 to 10 mmHg for 1 hour. The product was taken out from theflask after cooling, to yield a liquid polyol composition.

Comparative Example 3

A polyol mixture was prepared by adding 34.1 parts of diethylene glycol(a product of Mitsubishi Chemical Corporation) to 500 parts of apolytetramethylene glycol (PTMG1000, a product of Mitsubishi ChemicalCorporation) and was held at 100° C. PANDEX E used in ComparativeExample 2 was fused at 120° C. and was added to the polyol mixture (B)in the flask in amounts of 30%, 40%, 50% and 60% based on 70%, 60%, 50%and 40% of the polyol mixture, respectively. The resulting mixture wasblended and was subjected to dehydration at 100° C. to 105° C. at areduced pressure of 5 to 10 mmHg for 1 hour. The product was taken outfrom the flask after cooling, to yield a liquid polyol composition.

The mixtures prepared according to Examples 1 and 2 and ComparativeExamples 1, 2, and 3 were left to stand at 25° C. for one day, one week,three months and six months, and the appearances of the resultingmixtures were observed to determined the dissolution stability. TABLE 1Composition of (A) Polyaminochlorophenylmethane (B) Elapsed Content of(A) (% by weight) compound Polyol Time 30% 40% 50% 60% Example 1binuclear compound 65% PTMG1000 1 day A A A A trinuclear compound 28% 1week A A A A tetranuclear compound 7% 3 months A A A A 6 months A A AA-B Comparative binuclear compound 82% PTMG1000 1 day A A B C Example 1trinuclear compound 15% 1 week A A B C tetranuclear compound 3% 3 monthsA C C C 6 months A-B C C C Comparative MBOCA as binuclear compound 98%<PTMG1000 1 day A A C C Example 2 trinuclear compound 1%> 1 week A A C Ctetranuclear compound 1%> 3 months A C C C 6 months A-B C C C Example 2binuclear compound 65% PTMG1000 1 day A A A A trinuclear compound 28%DEG 1 week A A A A tetranuclear compound 7% 3 months A A A A 6 months AA A A-B Comparative MBOCA as binuclear compound 98%< PTMG1000 1 day A AB C Example 3 trinuclear compound 1%> DEG 1 week A A B C tetranuclearcompound 1%> 3 months A C C C 6 months A-B C C C(Criteria) A: transparent, pale brown solution B: hazy C: precipitatessuch as MBOCA

Table 1 shows that the polyol compositions of the present inventioncomprising the mixture (A) (65% of a binuclear compound, 28% of atrinuclear compound and 7% of a tetranuclear compound) dissolved in thepolyol (B) are transparent and pale brown solutions and exhibitexcellent dissolution stability over a long period of time. In contrast,the compositions according to Comparative Examples 1, 2, and 3 eachcomprising a higher content of MBOCA (binuclear compound) invite hazyturbidity in early stages and precipitation typically of MBOCA andexhibit deteriorated dissolution stability.

<Preparation 1> Preparation of Urethane Prepolymer (i)

A total of 500 parts of Collonate T-100 (toluene diisocyanate, a productof Nippon Polyurethane Industry Co., Ltd.) was placed in a flask. Atotal of 556.0 parts of PTMG1000 (polytetramethylene glycol, a productof Mitsubishi Chemical Corporation) and 93.4 parts of DEG (diethyleneglycol, a product of Mitsubishi Chemical Corporation) were added theretoin plural installments, followed by reaction at 60° C. under flow ofnitrogen gas for about 5 hours, to yield a urethane prepolymer (i)having an isocyanate equivalent of 400.

<Preparation 2> Preparation of Polyol Composition of the PresentInvention

In a flask were placed 500 parts of PTMG1000 (polytetramethylene glycol,a product of Mitsubishi Chemical Corporation) and 34.1 parts of DEG(diethylene glycol, a product of Mitsubishi Chemical Corporation), andthe mixture was held at 100° C. Separately, 534.1 parts of a mixture (A)containing 65% of a binuclear compound, 28% of a trinuclear compound and7% of a tetranuclear compound was fused at 120° C. and was placed intothe flask. The resulting mixture was subjected to dehydration at 100° C.to 105° C. at a reduced pressure of 5 to 10 mmHg for 1 hour. The productwas taken out from the flask after cooling and thereby yielded a liquidpolyol composition having an NH₂OH equivalent of 189.

Example 3

To 100 parts of the polyol composition prepared according to Preparation2 were added to 0.5 part of ion-exchanged water, 0.3 part of a foamstabilizer Toray Silicone SH-193 (a product of Dow Corning ToraySilicone Co., Ltd.) and 0.3 part of catalyst TOYOCAT-ET(N,N-dimethylaminoethyl ether, a product of Tosoh Corporation). Themixture was fully blended and was placed into a polyol tank of atwo-component mixing casting machine and was held to a temperature of60° C. Separately, the urethane prepolymer (i) prepared according toPreparation 1 was placed in a prepolymer tank of the two-componentmixing casting machine and was held at a temperature of 80° C. Using thetwo-component mixing casting machine, a total of about 260 g of theurethane prepolymer (i)(2) and the polyol composition (1) was cast in aweight ratio (urethane prepolymer (i)(2)/polyol composition (1)) of260/101.1 in a mold (120 mm by 280 mm by 15 mm) heated to 110° C. Themold was immediately covered with a lid and was left standing at 110° C.for 1 hour. The foamed molded article was taken out from the mold andwas subjected to aftercuring at 110° C. for 16 hours. The molded articlewas cut to a thickness of about 2 mm using a slicer and thereby yieldedan abrasive foam sheet having a uniform density distribution andexhibiting excellent physical properties.

Example 4

To 100 parts of the polyol composition prepared according to Preparation2 were added 0.7 part of ion-exchanged water, 0.3 part of a foamstabilizer Toray Silicone SH-193 (a product of Dow Corning ToraySilicone Co., Ltd.), 0.3 part of a catalyst TOYOCAT-ET(N,N-dimethylaminoethyl ether, a product of Tosoh Corporation) and 79.3parts of an abrasive grain HF-210 (cerium oxide, a product of ShinNippon Metal & Chemical Co., Ltd.). The mixture was fully blended andwas placed into a polyol tank of a two-component mixing casting machineand was held to a temperature of 60° C. Separately, the urethaneprepolymer (i) prepared according to Preparation 1 was placed in aprepolymer tank of the two-component mixing casting machine and was heldat a temperature of 80° C. Using the two-component mixing castingmachine, a total of about 260 g of the urethane prepolymer (i)(2) andthe polyol composition (1) in a weight ratio (urethane prepolymer(i)(2)/polyol composition (1)) of 270/180.6 was cast in a mold (120 mmby 280 mm by 15 mm) heated to 110° C. The mold was immediately coveredwith a lid and was left standing at 110° C. for 1 hour. The foamedmolded article was taken out from the mold and was subjected toaftercuring at 110° C. for 16 hours. The molded article was cut to athickness of about 2 mm using a slicer and thereby yielded an abrasivefoam sheet having a uniform density distribution and exhibitingexcellent physical properties.

Comparative Example 4

To 58.7 parts of PANDEX E (a product of Dainippon Ink and Chemicals,Inc.) containing 98% or more of MBOCA were added to 0.5 part ofion-exchanged water, 0.3 part of a foam stabilizer Toray Silicone SH-193(a product of Dow Corning Toray Silicone Co., Ltd.) and 0.3 part ofcatalyst TOYOCAT-ET (N,N-dimethylaminoethyl ether, a product of TosohCorporation). The mixture was fully blended at 120° C., was placed intoa polyol tank of a two-component mixing casting machine and was held ata temperature of 120° C. Separately, the urethane prepolymer (i)prepared according to Preparation 1 was placed in a prepolymer tank ofthe two-component mixing casting machine and was held at a temperatureof 80° C. Using the two-component mixing casting machine, a total ofabout 260 g of the urethane prepolymer component and the polyaminecomponent in a weight ratio of the former to the latter of 300/81.5 wascast in a mold (120 mm by 280 mm by 15 mm) heated to 110° C. Theprocedure of Example 3 was repeated and the product was cut to athickness of about 2 mm in order to yield a sheet-form abrasive.However, water in the tank evaporated to thereby fail to provide anabrasive foam sheet having a uniform density distribution.

Comparative Example 5

The procedure of Comparative Example 4 was carried out, except that thetemperature of the polyol tank containing the same MBOCA composition asComparative Example 4 was reduced to 90° C. at which water does notevaporate. However, MBOCA (PANDEX E, Dainippon Ink and Chemicals, Inc.)solidified to inhibit the mixing and casting of the two components.

Comparative Example 6

To 300 parts of the urethane prepolymer (i) held at a temperature of 80°C. were added 0.6 part of ion-exchanged water, 0.6 part of a foamstabilizer Toray Silicone SH-193 (a product of Dow Corning ToraySilicone Co., Ltd.) and 0.6 part of a catalyst TOYOCAT-ET(N,N-dimethylaminoethyl ether, a product of Tosoh Corporation). Themixture was blended and placed into a prepolymer tank and was held at atemperature of 80° C. PANDEX E (MBOCA, a product of Dainippon Ink andChemicals, Inc.) was placed into a polyol tank and was held at atemperature of 120° C. so as to avoid MBOCA from solidifying. Theprocedure of Example 3 was carried out using the two-component mixingcasting machine in order to produce a molded article, but the urethaneprepolymer reacted with water and solidified in the prepolymer tank,thus failing to carry out the molding process.

The hardness (Shore A), tensile strength, tensile stress, breakingelongation and tear strength of the abrasive foam sheets each having athickness of about 2 mm prepared according to Examples 3 and 4 weredetermined by the following methods. The results are shown in Table 2,indicating that each of the abrasive foams exhibits satisfactoryperformance as an abrasive foam.

“Hardness (Shore A)”: A sample was left standing in a room at atemperature of 23° C. and humidity of 50% for 24 hours or longer. Sixsample sheets having a thickness of 1.5 mm were stacked and subjected tothe determination of Shore A hardness according to Japanese IndustrialStandards (JIS) K7312.

“Tensile strength, tensile stress and breaking elongation”: A sample wasleft standing in a room at a temperature of 23° C. and humidity of 50%for 24 hours or longer. The properties were determined at a tensilespeed of 50 mm/min using a precision universal tester Shimadzu AutographAG-100KNG (a product of Shimadzu Corporation) according to JIS K7312.TABLE 2 Example 3 Example 4 Prepolymer (i) 260 270 Polyol composition100 100 Ion-exchanged water 0.5 0.7 Foam stabilizer Toray SiliconeSH-193 0.3 0.3 Catalyst TOYOCAT-ET 0.3 0.3 Grain HF-210 — 79.3 Specificgravity (g/cm³) 0.52 0.41 Hardness (Shore-A) 92 81 Tensile strength(MPa) 7.5 3.7 25% Modulus (MPa) 5.9 2.6 50% Modulus (MPa) 7 3.1 Breakingelongation (%) 58 75 Tear strength (kN/m) 32.6 22.4

INDUSTRIAL APPLICABILITY

The polyol compositions of the present invention each comprise specificamounts of the mixture (A) containing specificpolyaminochlorophenylmethane compound and the polyol (B), exhibit goodmiscibility and excellent dissolution stability and are liquid. Thisenables molding of foamed molded articles for abrasives using a simpletwo-component mixing casting machine. According to the presentinvention, water serving as a foaming agent can be added to the polyolcomposition containing MBOCA, and the composition for a two-componentcurable abrasive foam can be held to a temperature equal to or lowerthan the boiling point of water, thus avoiding water from evaporatingupon molding. The resulting abrasive foam has a uniform densitydistribution and exhibits excellent mechanical properties. Byincorporating a grain, the present invention can further provide anabrasive foam which is further useful, and a production method thereof.The abrasive foams of the present invention are useful for polishingprecision products such as glass and silicon semiconductor.

1. A polyol composition for a two-component curable abrasive foam,comprising (A) a polyaminochlorophenylmethane mixture and (B) a polyol,the polyaminochlorophenylmethane mixture (A) comprising: 50 to 70% byweight of a binuclear polyaminochlorophenylmethane compound representedby the following formula:

(wherein X independently represents a chlorine atom or a hydrogen atom),20 to 40% by weight of a trinuclear polyaminochlorophenylmethanecompound represented by the following formula:

(wherein X independently represents a chlorine atom or a hydrogen atom),and 5 to 10% by weight of a tetranuclear or higherpolyaminochlorophenylmethane compound represented by the followingformula:

(wherein X independently represents a chlorine atom or a hydrogen atom;and n represents an integer of 3 or greater), wherein thepolyaminochlorophenylmethane mixture (A) is uniformly dissolved in thepolyol (B), and wherein the weight ratio of (A) to (B) ((A)/(B)) standsat 30/70 to 60/40.
 2. The polyol composition for a two-component curableabrasive foam according to claim 1, wherein the polyol (B) is a polyolcontaining ether bond in a principal chain thereof and having amolecular weight of 100 to 1500 and/or a polyol containing methyl groupin a side chain thereof and having a molecular weight of 50 to
 500. 3.The polyol composition for a two-component curable abrasive foamaccording to claim 1, wherein the polyol (B) is at least one selectedfrom tetramethylene glycol and polypropylene glycols.
 4. A compositionfor a two-component curable abrasive foam, comprising the polyolcomposition (1) according to claim 1, a polyisocyanate (2) and water(3).
 5. The composition for a two-component curable abrasive foamaccording to claim 4, wherein the polyisocyanate (2) is anisocyanate-group-containing urethane prepolymer having an isocyanateequivalent of 300 to
 580. 6. The composition for a two-component curableabrasive foam according to claim 4, wherein the polyisocyanate (2) is atoluene diisocyanate-type urethane prepolymer containing a terminalisocyanate group.
 7. An abrasive foam, as a foamed and cured product ofthe composition for a two-component curable abrasive foam according toclaim 4, wherein the abrasive foam has a specific gravity of 0.3 to 1.2.8. A method for producing an abrasive foam, comprising the steps ofcasting the composition for a two-component curable abrasive foam ofclaim 4 in a mold, and foaming and curing the composition.